3D OCT Internal Clinical Analysis of Posterior Adhesive Ceramic Restorations

Objectives: The objective of this study was to use Optical Coherence Tomography (OCT) to clinically quantify the internal adaptation, ceramic and cement thickness and internal interfacial gaps of adhesive ceramic restorations at specific locations within the tooth.
Methods: A clinical trial assessing a dental adhesive and dual-curing composite resin cement (Adhese Universal / Variolink Esthetic, IvoclarVivadent) for cementation of posterior CAD/CAM lithium disilicate ceramic restorations was performed (Sorensen et al. J Dent Res 2019;98(A):2811).
Yoshida Dental OCT (Japan) imaging was performed on 7 crowns (Cr) and 7 onlays (On) at 6-24 month recall appointments. For each restoration, the Restoration Thickness (RT) and Cement Thickness (CT) at 3 functional locations were measured; Non-Supporting Cusp (NSC), Supporting Cusps (SPC) and Central Fossa (CF) (Amira software). At each location, cement-preparation Interfacial Gap Length (IGL) was also measured and ranked. The frequency of gap-free interfaces in relation to the cemented substrate (tooth vs. base material) was evaluated. Chi-square and Haberman’s residual analysis were performed to investigate the relationship between interfacial gap, functional location and cemented substrate (SPSS).
Results: The measured restoration and cement thicknesses were shown in table. Chi-square test demonstrated that Cr-IGL was significantly different among the 3 functional locations (p<0.05), while On-IGL was not. Zero-rank Cr-IGLs were frequently observed at CF but rarely at SPC (p<0.01). There was a difference in gap formation between base-cement and tooth-cement (p<0.05); 7 of 7 Cr base-cement interfaces and 5 of 7 On base-cement interfaces were gap-free, while only 2 of 7 and 1 of 7 tooth-cement interfaces were gap-free, respectively. Occasionally, gap formation between the base material and tooth surface was observed.
Conclusions: OCT successfully provided clinical information regarding ceramic thickness, cement thickness and interfacial adaptation. Frequency and degree of interfacial gaps were influenced by functional locations and substrates, although the tendencies differed depending on restoration configuration. Base materials could improve the interfacial adaptation. There was significantly less interfacial gap formation between base-cement compared to tooth-cement.